Stone tombs could have been used as telescopes that enabled prehistoric communities to set their calendar thousands of years before Galileo, scientists have proposed.

Astronomers believe the impressive passage graves of the Neolithic period provided a unique window from which to view the stars with unprecedented clarity. Researchers at Nottingham Trent University and the University of Wales Trinity Saint David suggest that standing at the centre of a pitch black tomb, and looking out through the entrance, would have allowed even faint stars to become visible.

University of Wales Trinity St. David

The team is currently studying 6,000-year-old graves in Carregal do Sal, Portugal, where 13 passage graves are thought to be aligned with Aldebaran, the brightest star in the constellation Taurus. Dr. Fabio Silva, a lecturer in Skyscapes, Cosmology and Archaeology at the University of Wales, believes the appearance of Aldebaran signalled the start of the summer migration.

“To accurately time the first appearance of this star in the season, it is vital to be able to detect stars during twilight,” said Silva.

“Studies have confirmed that the vast majority of passage graves in Portugal are oriented in such a way as to align with two or three stars, the most important of which was Aldebaran. It is possible that more passage graves, throughout Europe and the UK, also align to bright stars, possibly even Aldebaran. The star rising would have had a particularly important meaning for these communities.

NASA / AFP / Getty Images

“Rock art and paintings, some of which are present inside similar passage graves, could and have been interpreted as red stars, much like Aldebaran itself.”

Passage graves are a type of megalithic tomb composed of a chamber of large interlocking stones, reached by a long narrow entrance.

The burial chambers are thought to have been sacred, and may have been used for rites of passage, where the initiate would spend the night inside the tomb, which was lined with the remains of the tribe’s ancestors.